Policeman escorting Pakistani polio team killed

PESHAWAR, Pakistan 
Gunmen riding on a motorcycle shot and killed a police officer escorting polio workers during a U.N.-backed vaccination campaign in northwestern Pakistan on Tuesday, the police said.

The attack took place as dozens of polio workers - including several women - were going door-to-door to vaccinate children in Gullu Dheri village of Swabi district in the Khyber Pakhtunkhwa province, said senior police officer Izhar Shah.

"The polio workers were terrified and immediately went back to their homes after the attack," Shan told The Associated Press. "The anti-polio drive in that village has been suspended."

It was the second day of a three-day campaign against polio that was launched by the provincial government. No one claimed responsibility for the killing, but suspicion fell on militants.

Some Islamic militants oppose the vaccination campaign, accuse health workers of acting as spies for the U.S. and claim the polio vaccine is intended to make Muslim children sterile.

In December, gunmen killed nine polio workers in similar attacks across Pakistan, prompting authorities to suspend the vaccination campaign in the troubled areas. The latest campaign in Khyber Pakhtunkhwa was launched Monday to give oral drops to those children who had missed it the first time round.

Pakistan is one of only three countries where the crippling disease is endemic. The virus usually infects children living in unsanitary conditions; it attacks the nerves and can kill or paralyze. As many as 56 polio cases were reported in Pakistan during 2012, down from 190 the previous year, according to the United Nations.

Most of the new cases in Pakistan were in the northwest, where the presence of militants makes it difficult to reach children.